The subject matter disclosed herein relates to a technique which obtains dual energy images at an X-ray CT apparatus and an image processing apparatus therefore.
It has been known that a tomographic image of a conventional X-ray CT apparatus is image-reconstructed using a CT value (Hounsfield number). There has also been known a technique which obtains an image (hereinafter called “dual energy image”) based on each of CT values respectively obtained using an X ray of an energy spectrum generated by an X-ray tube using a high X-ray tube voltage and an X ray of an energy spectrum generated by the X-ray tube using a low X-ray tube voltage (refer to, for example, Japanese Unexamined Patent Publication No. 2004-65975). Described more specifically, it has been known that according to the present technique, since X-ray absorption coefficients of substances in a subject are different depending on the X-rays different in energy spectrum, a difference is taken so that the substances lying in the subject are emphasized.